Residential and commercial building construction uses a variety of building materials and construction techniques to complete the structure. In some building projects, lumber or metal studs are used for the framing. The frame structure is held together with nails, screws, and bolts. An exterior siding such as stucco, wood, vinyl, brick, or aluminum is placed over the frame structure. Insulation is placed between the studs of the frame structure. The interior coverings such as drywall are affixed to the inside of the frame structure. The entire building project is typically performed on the construction site. The use of interior and exterior siding over frame is costly and labor and time intensive. Wood framing is of inferior quality and subject to insect damage and warping. Metal framing is thermally conductive which is undesirable in view of energy costs. The frame-based structure is susceptible to the effects of aging and storm damage. While frame construction has been dominant in the building industry for many years, other more cost effective and time efficient solutions are becoming more common.
One alternative building approach involves the use of hollow sectional forms, which are put together in the shape of the exterior wall. The hollow forms are filled with concrete and then disassembled when the concrete cures, leaving a concrete wall. The concrete wall is long-lasting and strong against the elements, but the forms are generally expensive to setup.
Another building approach involves the use of pre-fabricated building panels which are manufactured off-site and then assembled together on-site. One such building panel is discussed in U.S. Pat. No. 6,796,093 as having a plurality of I-beam-shaped metal struts spaced about 18 inches apart with insulating foam blocks disposed between the metal struts. The metal struts have cut-outs along the length of the I-beam to reduce the total metal area and associated thermal conductivity. FIG. 1 shows exemplary prior art I-beam metal strut 12 between foam blocks 14. While the structural panel has good load-bearing characteristics, the I-beam metal strut 12 is continuous across foam block 14, at least through portions of the metal struts and, consequently, is thermally conductive through the continuous metal areas. Since I-beams 12 go completely through foam blocks 14, heat and cold will conduct from one side to the other side of the wall structure. In the summer, I-beam 12 conducts heat from the exterior to the interior of the building. In the winter, I-beam 12 conducts cold from the exterior to the interior of the building. In any case, the I-beam construction decreases the thermal insulation property of the building panels.
In another application, a retaining wall can be built to hold back earth, water, or otherwise create a barrier. The barrier wall can be used for security purposes, e.g. to control ingress and egress of people and objects to a restricted area, such as a military base, secure facility, or hazardous area. In the case of a prison, the barrier wall serves to keep people and objects contained within a designated area. The barrier wall can be used for privacy purposes to create a visual barrier around a private home community or business development, as well as control ingress and egress to designated entrances and exits. In another application, a barrier wall can be built one or both sides of a roadway adjacent to a residential or commercial area. The barrier wall serves to block traffic noise, as well as form a visual and safety barrier. The barrier prevents pedestrians and animals from crossing the roadway. By blocking traffic noise, the barrier wall serves to maintain property value and enable quiet enjoyment of the area adjacent to the roadway.
To construct a barrier wall, a footing is formed along an entire length of the barrier wall for structural support. The footing can be concrete, natural materials, or man-made materials. The footing is typically wider than the wall and formed below ground level. In the case of a concrete footing, the ground is excavated to a solid foundation and a rebar structure is formed in the footing area by wiring together individual rebar rods. A portion of the rebar extends above the footing to tie into the wall structure. The footing area is filled with concrete to enclose the rebar structure.
A concrete form is placed over the footing. The concrete form typically contains wood or fiberglass panels separated by a width of the wall, e.g. 8-12 inches. Construction design rules typically limit the height of the concrete form to 8 feet and length to 15 feet. A rebar structure is formed between the wood panels by wiring together individual rebar rods. The rebar structure is also tied to the rebar extending from the footing. The wood panels are tied together at a plurality of locations across the empty space between the wood panels for strength during the subsequent concrete pour. Again, concrete is poured between the wood panels to enclose the rebar structure. When the concrete is cured, the wood panels are removed leaving a first rebar-reinforced concrete barrier wall section with a length of 15 feet and height of 8 feet.
If the barrier wall specification is higher than the concrete form limitation, then a second concrete form with wood panels is placed over the first concrete wall section. Again, a rebar structure is formed between the wood panels by wiring together individual rebar rods. The rebar structure is also tied to the rebar extending from the first concrete wall. Concrete is poured between the wood panels of the second concrete form to enclose the rebar structure. When the concrete is cured, the wood panels are removed leaving a second rebar-reinforced concrete barrier wall disposed over the first concrete wall section. The barrier wall now has the same length of 15 feet but with an extended height of 16 feet. Of course, another concrete wall section must be formed on the footing to extend the length of the wall, and additional concrete wall sections must be formed vertically to extend the height of the wall. The process continues section-by-section, both horizontally and vertically, until the wall reaches the total height and length required in the barrier wall specification.
The aforedescribed process of forming concrete barrier walls is time consuming and expensive. The barrier wall must be built horizontally and vertically section-by-section and may extend for many miles in the case of barrier walls along roadways. Significant labor and material costs are required to form the footing, set the concrete forms with rebar, pour the concrete, and allow adequate curing time for each section. A number of vocational tradesmen are needed, including masonry, heavy equipment operators, carpenters, painters, safety personal, insurance, permits, etc. Most if not all work must be performed at the job site, which may experience weather delays, material delays, work coordination issues, terrain issues, as well as subjecting traffic and residents to construction issues.